Sea's acidity rising 100 times faster than in past, UNESCO says

The world's oceans are absorbing carbon dioxide and becoming more acidic at a rate 100 times faster than in the past, putting fisheries at risk as well as the people whose livelihoods depend on them, the United Nations said.

"Our oceans are sick," said James Orr, who chaired a United Nations Educational, Scientific and Cultural Organization meeting last week in Monaco. "Decision-makers need to sit up and take notice."

As carbon dioxide, which is emitted from burning fossil fuels, dissolves in the sea, the water becomes more acidic, making it more difficult for corals and other marine life to build shell material. Humans will have added 5 trillion tons of carbon into the atmosphere by 2400 if carbon-dioxide emissions continue at their current rate, according to James Zachos, professor of Earth and planetary sciences at the University of California, Santa Cruz.

Ocean surface waters are 30 percent more acidic now than pre-Industrial Revolution levels, UNESCO said today on its Web site. By 2030, water in the southern oceans will be corrosive to shellfish, threatening the main source of food for Pacific salmon.